Amputations about the Knee

BKA / Below Knee Amputation / Transtibial


Best results

- long posterior musculocutaneous flap 

- well cushioned mobile muscle mass

- full thickness skin

- very anterior scar



- non-ambulator

- get FFD

- better with through knee amputation


Advantages over AKA 


1.  Good Healing 

- > 90% in DM with BKA


2.  Higher prosthesis wearing rates 

- 74% vs 26% for AKA


3.  Reduced energy required for walking

- 74% BKA < 45 year old walk > 1 mile


4.  Reduced mortality 

- 10% vs 30%





- no tourniquet if PVD

- tourniquet in trauma (patients can bleed to death)


Posterior flap

- mark long posterior flap

- avoid suture line over anterior aspect of tibia / problems frequent here


Anterior flap

- short anterior flap at level of tibia cut

- want to extend posterior flap over distal tibia


Anterior Dissection

- find anterior NV bundle between T anterior and EHL

- deep peroneal nerve on interossesous bundle

- divide anterolateral muscles at tibial level to avoid bulbous stump


Tibial resection

- 15cm stump from joint

- no advantage in > 15cm as skinny poor stump

- < 3cm stump worse than through knee

- sharp dissect periosteum 2 cm above

- leave periosteal flap so can suture muscle flap to it

- bevel sharp edges


Fibula resection

- divide fibula 2cm above this

- need to ensure is stable (well connected to tibia via interosseous membrane)

- if not may need to create arthrodesis in young active patient


Fibular arthrodesis / unstabile fibula

- create wedge in tibia

- elevate periosteal sleeve to place over top of graft

- use 1 cm of fibula

- can get pain for 6-9 months as the graft unites


Posterior dissection

- find posterior tibial artery and tibial nerve

- on tibialis posterior between FDL and FHL

- divide deep muscles and allow to retract

- remove soleus leaving only gastrocnemius flap

- ensure vascularity flap


Myodesis gastrocnemius

- through drill holes in tibia and to periosteum of tibia

- fascial repair over muscle bellies



- over drain

- DPC if trauma or infection

- careful pressure dressings with tape to ensure good shaping


Through Knee




1.  Non ambulators

- aids sitting balance

- avoids FFD and subsequent problems


2.  < 3-5 cm tibia


3.  ST tissue loss means BKA not possible


Advantage over AKA

- improved socket suspension

- longer lever arm 

- muscle balanced amputation

- end-bearing potential

- less volume changes



- asymmetrical knee joint

- bulky prosthesis

- overcome by newer prosthetic techniques





- patients can bleed to death



- equal anterior / posterior flaps

- 5cm distal to knee joint

- fish mouth

- can make posterior flap slightly longer



- depends on technique 

- original method is to retain patella

- Mazet & Hennessy excise patella from tendon


Knee dissection

- divide PT off tibial tuberosity

- cruciates and collaterals divided at level of below meniscus

- aim to keep them long

- this preserves the rich proprioceptive function of the capsule


Deep dissection

- divide posterior capsule

- find and ligate popliteal artery and vein

- finding tibial nerve, tension, sharp divide, diathermy



- PT sutured to cruciate stumps

- biceps tendon sutured to PT

- gastrocnemius to anterior capsule


Above Knee Amputation / Transfemoral


Vumedi video





Failed / septic TKR



- energy expenditure increased by 65%

- residual abduction as Adductor Magnus released from adductor tubercle

- myodesis in 10o adduction maintains abductor strength and prevents abductor lurch

- residual flexion due to quads / hamstring inbalance





- sandbag under buttock

- avoid having leg in flexed position



- actually want scar slightly posterior, with larger anterior muscle flap

- fish mouth

- larger anterior flap skin and muscle 



- cut quadriceps tendon above patella

- detach sartorius / gracilis / hamstrings 2 cm longer for myodesis

- detach Adductor Magnus



- femoral artery below vas medialis in Hunter's canal / subsartorial canal

- profunda femoris posterior to femur

- can cut femur first to give access to NV bundles


Femoral transection

- save all possible femoral length

- increasing length increases muscle strength

- minimum 12 cm above knee to fit in prosthetic knee joint

- has to be >18 cm from GT or fixation difficult

- if stump < 5 cm below lesser trochanter then fitted as hip disarticulation

- smooth anterior edge of distal femur to avoid stump issues


Adductor myodesis

- maintain stump in 10° adduction

- anatomical position

- suture through drill holes in lateral femoral cortex


Anterior musculature

- myodesis of quadriceps to posterior femur avoids FFD

- through anterior drill holes


Posterior musculature

- myoplasty to A Magnus or quads


Soft spica

- suspend dressing from waist

- support medial thigh



- positioning important to prevent contractures

- stump flat on bed

- intermittent prone positioning